Make variable capacitors by stretching aluminum cans
Sometimes when you need a component, the best way to get it is to build it yourself. [North Carolina Prepper] did just that, creating their own trombone-style variable capacitor by stretching aluminum drink cans.
The requirement was for a 26 pF to 472 pF capacitor, for radio transmission from 7 MHz to 30 MHz. The concept was to use two drink cans, one sliding inside the other, like a capacitor, with an insulating material in between.
To achieve this, a cheap tailpipe expander tool was used to stretch a regular can to the point where it would easily slide over an unmodified can, plus extra space to allow for a plastic insulating sheet between the two. Annealing the box is important to keep it from tearing, but basically it's a simple process.
The resulting paper clip capacitor can easily be inserted and removed to change its capacitance. The build as seen here hit 33pF to 690pF without much fuss, not far off the specs [North Carolina Prepper] was aiming for.
Radio amateurs are very creative in building their own equipment, especially when it comes to variable capacitors. Video after the break.
[Thanks to Seebach for the tip!]
Sometimes when you need a component, the best way to get it is to build it yourself. [North Carolina Prepper] did just that, creating their own trombone-style variable capacitor by stretching aluminum drink cans.
The requirement was for a 26 pF to 472 pF capacitor, for radio transmission from 7 MHz to 30 MHz. The concept was to use two drink cans, one sliding inside the other, like a capacitor, with an insulating material in between.
To achieve this, a cheap tailpipe expander tool was used to stretch a regular can to the point where it would easily slide over an unmodified can, plus extra space to allow for a plastic insulating sheet between the two. Annealing the box is important to keep it from tearing, but basically it's a simple process.
The resulting paper clip capacitor can easily be inserted and removed to change its capacitance. The build as seen here hit 33pF to 690pF without much fuss, not far off the specs [North Carolina Prepper] was aiming for.
Radio amateurs are very creative in building their own equipment, especially when it comes to variable capacitors. Video after the break.
[Thanks to Seebach for the tip!]
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